Chaxapeptin, a Lasso Peptide from Extremotolerant Streptomyces leeuwenhoekii Strain C58 from the Hyperarid Atacama Desert

Abstract

Lasso peptides are ribosomally synthesized and post-translationally modified peptides (RiPPs) that possess a unique "lariat knot" structural motif. Genome mining-targeted discovery of new natural products from microbes obtained from extreme environments has led to the identification of a gene cluster directing the biosynthesis of a new lasso peptide, designated as chaxapeptin 1, in the genome of Streptomyces leeuwenhoekii strain C58 isolated from the Atacama Desert. Subsequently, 1 was isolated and characterized using high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance methods. The lasso nature of 1 was confirmed by calculating its nuclear Overhauser effect restraint-based solution structure. Chaxapeptin 1 displayed a significant inhibitory activity in a cell invasion assay with human lung cancer cell line A549.

Dual substrate‐controlled kinase activity leads to polyphosphorylated lasso peptides

“…3A), in agreement with previous assays of ThcoK with PadeA (13-23) [34]. When ThcoK was incubated with ATP and either PadeA (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) or deletion variant S-PadeA(13-23) DD22, only a singly phosphorylated peptide was significantly produced (Fig. 3B).…”

“…Plasmids were transformed into E. coli BL21(DE3) cells for expression and subsequent purification of Trx fusion proteins, followed by cleavage with TEV protease and further purification as described above for S-ThcoA and S-SyanA. PadeA (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) and PadeA(13-23)-PO 2À 3 were purchased from Biomatik (Cambridge, Ontario, Canada) (> 95% purity).…”

“…3A, ThcoK transferred up to three phosphate groups onto S-ThcoA (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) when ATP served as the phosphate donor; however, a singly phosphorylated peptide appeared as the main product. Conversely, when ATP was replaced with GTP, singly and doubly phosphorylated peptides were produced in nearly equal amounts.…”

“…Extensive post-translational modifications enrich the structural diversity and, thereby, chemical stability and bioactivity of such compounds. Lasso peptides are members of an intriguing family of RiPPs that possess an unusual lariat knot-like structure [6][7][8][9][10][11][12][13][14]: the N terminus of the peptide is covalently cyclized with an acidic side chain to form a 7-, 8-, or 9-residue macrolactam ring; the C terminus is threaded through this ring and trapped by bulky side chains, thus stabilizing the entropically disfavored conformation (Fig. 1A) [9][10][11]13,[15][16][17][18][19][20][21][22][23][24].…”

Natural product diversity of actinobacteria in the Atacama Desert

“…Another class of compounds amenable to genome mining are ribosomally synthesized and post-translationally modified peptides (RiPPs). A recent example is the discovery of a lasso peptide through the identification of the lasso peptide cpt gene clusters, which was used in the successful isolation and identification of chaxapeptin from S. leeuwenhoekii strain C58 (Elsayed et al 2015).…”